1. Field of the Invention
The present invention pertains to the field of devices that reduce the transmission of radiation, and particularly to devices that reduce the transmission of infrared light.
2. Description of the Related Art
Several patents and publications are cited in this description in order to more fully describe the state of the art to which this invention pertains. The entire disclosure of each of these patents and publications is incorporated by reference herein.
Glass laminated products or “safety glass” have contributed to society for almost a century. Safety glass is characterized by high impact and penetration resistance, and by minimal scattering of glass shards and debris upon shattering. The laminates typically consist of a sandwich of a polymeric film or sheet interlayer that is placed between two glass sheets or panels. One or both of the glass sheets may be replaced with optically clear rigid or non-rigid polymeric sheets such as sheets of polycarbonate materials or polyester films. Safety glass has further evolved to include more than two layers of glass and/or polymeric sheets bonded together with more than one interlayer.
Beyond the well known safety glass commonly used in automotive windshields, glass laminates are incorporated as windows into trains, airplanes, ships, and nearly every other mode of transportation. The architectural use of safety glass has also expanded rapidly in recent years, as designers incorporate more glass surfaces into buildings.
Society continues to demand more functionality from laminated glass products beyond its optical and decorative capabilities and safety characteristics. One desirable goal is the reduction of energy consumption within structures, such as automobiles or buildings through the development of solar control glazing. Because the near infrared spectrum is not sensed by the human eye, a typical approach has been to develop glass laminates that prevent a portion of solar energy from the near infrared spectrum from entering the structure. For example, the energy expended on air conditioning may be reduced in structures equipped with solar control windows that block a portion of the near infrared spectrum without a reduction or distortion of the transmitted visible light spectrum.
Solar control in glass laminates may be achieved through modification of the glass or of the polymeric interlayer, by the addition of further solar control layers, or combinations of these approaches. One form of solar control laminated glass includes metallized substrate films, e.g., polyester films that have electrically conductive aluminum or silver metal layers. The metallized films generally reflect light of the appropriate wavelengths to provide adequate solar control properties. Metallized films are commonly manufactured by vacuum deposition or sputtering processes that require a high vacuum apparatus and a precision atmosphere controlling system. In addition to infrared light, metallized films also reflect certain radio wavelengths, thus impairing the function of radio, television, global positioning systems (GPS), automated toll collection, keyless entry, communication systems, automatic garage openers, automated teller machines, radio frequency identification (RFID), and like systems commonly used in automobiles or other structures that may be protected by solar control laminated glass. This impairment is a direct result of the metal layers being continuous and, therefore, electrically conductive.
A more recent trend has been the use of metal containing nanoparticles that absorb rather than reflect infrared light. To preserve the clarity and transparency of the substrate, these materials ideally have nominal particle sizes below about 200 nanometers (nm). Because these materials do not form electrically conductive films, the operation of radiation transmitting and receiving equipment located inside structures protected by this type of solar control glazing is not impeded. The addition the nanoparticles into the polymeric interlayers necessarily complicates the processes by which these laminates are produced, however.
Infrared absorbing phthalocyanines and phthalocyanine-based materials are known for use in optical information recording media, sometimes in conjunction with a binder resin that may comprise polyvinyl butyral. Recent examples of patents in this art area include U.S. Pat. Nos. 6,057,075; 6,197,472; 6,576,396; 6,197,464; 6,207,334; 6,238,833; 6,376,143; 6,465,142; and 6,489,072.
Alkoxy-substituted phthalocyanine compounds have also been used as infrared absorbing materials in optical information recording media, sometimes in conjunction with a binder resin. See, for example, U.S. Pat. Nos. 4,769,307; 5,296,162; 5,409,634; 5,358,833; 5,446,142; 5,646,273; 5,750,229; 5,594,128; 5,663,326; and 6,726,755; and European Patent No. 0 373 643.
Also known are various solar control devices that include organic infrared absorbing materials such as phthalocyanine compounds. For example, the Avecia Corp., Wilmington, Del., markets several phthalocyanine compounds as infrared absorbers for incorporation into glazing materials such as glass, plastics and film coatings. For examples of phthalocyanine containing glass laminate interlayer compositions, see U.S. Pat. Nos. 5,830,568; 6,315,848; 6,329,061; and 6,579,608; U.S. Patent Application Publication No. 2004/0241458; and International Patent Application Publication No. 2002/070254.
Infrared absorbing naphthalocyanine materials have also been generally disclosed for use in optical information recording media, which may include binder resins. For example, see U.S. Pat. Nos. 4,492,750; 4,529,688; 4,769,307; 4,886,721; 5,021,563; 4,927,735; 4,960,538; 5,282,894; 5,446,142; 5,484,685; 6,197,851; 6,210,848; 6,641,965; 5,039,600 and 5,229,859. Certain naphthalocyanine materials dispersed within binder resins, which may include polyvinyl butyral, have been disclosed within the art. For example, U.S. Pat. No. 4,766,054 describes an optical recording medium that includes certain naphthalocyanine dyes.
Phthalocyanine-type and naphthalocyanine-type infrared absorbers are often relatively inefficient solar control agents, however, because they are highly colored. Stated alternatively, many phthalocyanines and naphthalocyanines have a significant level of absorption of visible wavelengths.
It remains desirable, therefore, to provide new solar control laminates that reduce the transmission of infrared energy and provide more efficient transmission of visible light and radio frequencies.